Equine Herpes Myeloencephalopathy (EHM) Updates:


EHV-1 Quarantine in Sacramento County

July 30, 2021: The 15-year-old Warmblood mare from the index premises that attended and was asymptomatic at the Sonoma County event and displayed mild neurologic signs on July 27th has had a confirmed second negative EHV-1 test 24 hours later and returned home to the index premises in stable condition and continues to recover. The three other neurologic horses in isolation at the offsite veterinary hospital are also alive in stable condition, and were retested on July 29th and/or July 30th, and confirmed negative for EHV-1. One additional horse at the index premises, a 5-year-old Warmblood gelding, that attended the Sonoma County event and remains asymptomatic was tested on July 28th and confirmed positive for EHV-1 on July 30th, and has been isolated at the index premises.  

No clinical signs from any additional horses from the Sonoma County event or the home premises have been reported at this time. CDFA was onsite on the index premises on July 29th and continues to actively monitor this situation. 

 

The total number of confirmed cases in this incident are: 1 (one) confirmed EHM case (EHV-1 positive with neurologic signs), 1 (one) confirmed asymptomatic EHV-1 case, and 1 (one) confirmed febrile-only EHV-1 case, and 4 (four) presumptive positive cases that were subsequently confirmed negative.  In total, one (1) horse in this incident has been euthanized and the other affected horses are alive and currently recovering under veterinary care.

 

July 28, 2021: One additional 15-year-old Warmblood mare from the index Sacramento county home premises who attended, and was asymptomatic at, the Sonoma county event displayed mild neurological signs and was transported to an offsite veterinary hospital in isolation on July 27th and confirmed negative for EHV-1 on July 28th.  No additional horses from the Sonoma county event or the home premise have shown clinical signs at this time. CDFA continues to actively monitor this situation.


July 27, 2021: The eighteen (18) horses from the index case’s origin premises that attended the Sonoma county event returned to their home premises in Sacramento County on Sunday July 25th and are quarantined.  The horse in this cohort with a fever on July 24th with tests pending was confirmed positive for EHV-1 and remains isolated at the home premises, and has been afebrile since Saturday July 24th.

 On Monday July 26th, CDFA staff performed a site visit at the home premises in Sacramento county. One horse on the Sacramento home premises that did not attend the Sonoma county event and previously tested positive for EHV-1 (fever only) became neurologic on Monday July 26th and has been sent to an offsite veterinary hospital for treatment. He is in stable condition and was confirmed negative for EHV-1 on Monday, July 26th. One additional horse at the home premises that did attend the Sonoma County event and has remained afebrile also became neurologic on Monday July 26th and has been sent to an offsite veterinary hospital for treatment, and was confirmed negative for EHV-1 on Monday July 26th. She is currently alive and in stable condition.

 

One additional horse that was housed in the same barn at the Sonoma County event presented with fever and mild neurologic signs on Saturday July 24th and was sent to an offsite veterinary hospital for treatment was confirmed negative for EHV-1 on Monday July 26th.  He is currently alive and in stable condition. The three remaining horses in this same barn returned to their home premises on Saturday July 25th and are isolated with temperature monitoring and no fevers or clinical signs have been detected.

 

The total number of confirmed cases in this incident are: 1 (one) confirmed EHM case (EHV-1 positive with neurologic signs), 1 (one) new confirmed EHV-1 case (fever and/or edema) only, with 4 (four) previously presumptive positive EHV-1 cases (fever and/or edema only) that have subsequently retested and confirmed negative. In total, one (1) horse in this incident has been euthanized and the other affected horses are alive and under veterinary care.  

   

As of Monday July 26th, there is no evidence of ongoing EHV-1 spread at the Sonoma County facility following removal of all known affected and immediately exposed horses.  A complete facility quarantine will not be implemented there unless ongoing disease spread is confirmed.   The decision for individuals to attend an event at this premises within this timeframe should be discussed with their veterinarians and will be at the owner’s and/or trainer’s own discretion and risk.  

 

CDFA recommends that any horses that attended or are currently attending the Sonoma County event be temperature monitored for at least seven (7) days and are isolated at least thirty (30) feet from other horses when they return to their home properties.

 

CDFA was onsite at the Sonoma County event premises on July 27th, and continues to actively monitor the situation.

 

July 25, 2021:   A 6-year-old Warmblood mare displaying neurological signs has been confirmed positive for EHM secondary to EHV-1. She attended a show in Sonoma County from 7/19-7/24 but did not compete, and event management has notified all participants to monitor temperatures twice daily and report any fevers or neurologic signs to their veterinarians and CDFA, as well as isolate all horses returning from shows at their home premises for at least 7 days.  CDFA was onsite, and 19 exposed horses from the index mare’s barn were removed from the show facility and have been isolated and quarantined at the home premises in Sacramento County with the remaining 18 horses at the home premises with twice daily temperature monitoring and enhanced biosecurity measures. Three (3) horses (corrected from six) from the home premises displaying fever and/or limb edema have also tested positive for EHV-1. A 15-year-old Warmblood gelding at the home premises that was febrile and tested positive for EHV-1 began displaying neurological signs, ataxia, urine dribbling, and cranial nerve deficits and was moved to isolation under quarantine at a veterinary hospital for care.  CDFA continues to actively monitor the situation.

RELEASED: EHV-1 Quarantine in Santa Clara County

April 7,  2021:  No additional cases to report.  As there were no additional cases for fourteen (14) days on the home premises, the quarantine was released.

April 1,  2021:  No additional cases to report. CDFA continues to monitor the situation closely.

March 24, 2021:   A 21-year-old Quarter Horse mare from Santa Clara County displaying neurological signs was confirmed positive for Equine Herpesvirus-1 on March 23 rd. The horse is alive and is being treated in isolation at a veterinary hospital. The home premises has been quarantined with enhanced biosecurity measures in place and twice daily temperature monitoring. The clinical horse has no recent travel history and no links to any other EHV-1 cases. The home premises hosted an event on March 21 st, and one asymptomatic horse from the home premise competed in an event from March 19 th – 21 st.  Event managers have been notified, and are encouraging all owners of potentially exposed horses to perform twice daily temperature monitoring, limit movement, and practice enhanced biosecurity measures for the next 14 days. CDFA will be onsite and continue to actively monitor exposed horses.

 

RELEASED: EHV-1 Quarantine in Sonoma County

March 29, 2021:  No additional cases to report. As there were no additional cases for fourteen (14) days on the home premises, the quarantine was released.

March 22,  2021:  No additional cases to report. CDFA continues to monitor the situation closely.

March 16, 2021:   A 21-year-old Warmblood mare from Sonoma County displaying neurological signs was confirmed positive for Equine Herpesvirus-1 (neuropathogenic strain) on March 15 th; the horse is alive and is being treated in isolation at a veterinary hospital. Horses on the home premises have been quarantined with enhanced biosecurity measures and twice daily temperature monitoring. There is no known risk of exposure out of this facility to any local events. The clinical horse has no recent travel history and no links to any other EHV-1 cases. CDFA will continue to actively monitor exposed horses.

 

RELEASED: EHV-1 Quarantine in San Bernardino County

March 29, 2021:  No additional cases to report. As there were no additional cases for fourteen (14) days on the home premises, the quarantine was released.

March 22, 2021:  No additional cases to report. CDFA continues to monitor the situation closely.

March 16, 2021:   A 10-year-old Arabian gelding  in San Bernardino county displaying neurological signs was confirmed positive for Equine Herpesvirus-1 (EHV-1 non-neuropathogenic strain); the horse is alive and under veterinary care. One additional horse on the property tested positive for EHV-1 with neurological signs and was euthanized due to the severity of clinical signs. Following an assessment of the home premises in San Bernardino County by CDFA personnel, twenty-two (22) potentially exposed equids have been quarantined with enhanced biosecurity measures and twice daily temperature monitoring. This premises is a private facility with no recent movement on or off the property and these cases have no known links to any other EHV-1 cases. CDFA will continue to actively monitor exposed equids.

 

RELEASED: EHV-1 Quarantine in Los Angeles County

 

April 2, 2021:  The index horse met the parameters of receiving two (2) negative tests seven (7) days apart so the quarantine has been released.

March 24, 2021:  As there were no additional cases for fourteen (14) days on the home premises, the quarantine for the boarding facility has been released. The initial index horse remains positive on testing for EHV-1 so will continue its quarantine at its isolation premises until it has two (2) negative tests seven (7) days apart. 

March 22, 2021:  No additional cases to report. CDFA continues to monitor the situation closely.

March 15, 2021:   No additional cases to report. CDFA continues to monitor the situation closely.

March 10, 2021:  A 20 -year-old Warmblood gelding in Los Angeles County displaying neurological signs was confirmed positive for Equine Herpesvirus-1 (EHV-1 non-neuropathogenic strain) on March 9 th; the horse is alive and under veterinary care. Following an assessment of the home premises in Los Angeles County by CDFA personnel, forty-two (42) potentially exposed horses have been quarantined with enhanced biosecurity measures and twice daily temperature monitoring. The owners of all exposed horses have been notified and no additional cases have been identified at this time. CDFA will continue to actively monitor exposed horses.

RELEASED: EHV-1 Quarantine in Los Angeles County

February 26, 2021:  No additional cases to report. As there were no additional cases for fourteen (14) days on the home premises, the quarantine was released. There are no current EHM quarantines in California.

February 22, 2021:  No additional cases to report. CDFA continues to monitor the situation closely.

February 17, 2021:  No additional cases to report. CDFA continues to monitor the situation closely.

February 12, 2021:  An 11-year-old Tennessee Walking horse gelding in Los Angeles County displaying neurological signs was confirmed positive for Equine Herpesvirus-1 (EHV-1 non-neuropathogenic strain) on February 11th. The gelding was euthanized due to the severity of neurologic signs on February 7th. Seventy-two (72) potentially exposed horses at his home premises in Los Angeles County have been quarantined with enhanced biosecurity measures implemented, including twice daily temperature monitoring following site assessment by CDFA personnel. All horses on the premises had no recent show or travel history and all owners of exposed horses have been notified. No additional cases have been identified at this time, and CDFA will continue to actively monitor the situation.